JP2024033534A - battery cooling system - Google Patents

Abstract

A battery cooling system that uniformly cools a plurality of battery modules is provided. A battery cooling system 1 includes a battery case 10 having a plurality of accommodating parts 11 for accommodating each of a plurality of battery modules 2, and a main pipe through which cooling water discharged from a pump P flows. 20, a plurality of branch pipes 30 that are branched from the main pipe 20 and provided corresponding to each of the plurality of accommodating parts 11, and a plurality of branch pipes 30 that are provided at the tips of each of the plurality of branch pipes 30 and accommodated in the respective accommodating parts 11. The shorter the distance from the supply unit 40 that supplies cooling water to the battery module 2 and the pump P to the connection point 29 between the main pipe 20 and the branch pipe 30, the shorter the branch branching via the connection point 29. A flow rate control mechanism 50 that increases the pressure loss of the cooling water flowing through the pipe 30 is provided. [Selection diagram] Figure 1

Description

The present invention relates to a battery cooling system for cooling a battery including a plurality of battery modules.

Batteries generate heat due to power output and charging. Using the battery in such a state where it is generating heat causes a decrease in the performance of the battery. Furthermore, if the temperature of the battery exceeds a predetermined temperature, thermal runaway may occur. Therefore, techniques for cooling batteries have been studied (for example, Patent Documents 1 and 2).

Patent Document 1 describes a secondary battery cooling mechanism that can individually cool a plurality of secondary batteries. The secondary batteries cooled by this secondary battery cooling mechanism are equipped with a safety valve on the top surface of each housing that opens when the temperature reaches a predetermined temperature, and cooling water can be injected in opposition to this safety valve. A spray nozzle is arranged. When the temperature inside the housing reaches a predetermined temperature, a safety valve is activated, and cooling water flows into the interior of the secondary battery to cool the interior of the secondary battery.

Patent Document 2 describes a thermal runaway suppression system for secondary batteries. In this thermal runaway prevention system, the internal space of the casing is partitioned into a plurality of storage battery compartments, and a plurality of secondary battery modules are installed in each storage battery compartment. Piping from a cooling water supply source is provided to be branched for each storage battery compartment, and the branched piping is provided with a plurality of nozzles that discharge cooling water to each secondary battery module.

Japanese Patent Application Publication No. 2018-133134 Japanese Patent Application Publication No. 2018-63766

In the secondary battery cooling structure described in Patent Document 1 and the secondary battery thermal runaway prevention system described in Patent Document 2, a plurality of injection nozzles (nozzles) are provided branching from one pipe. For this reason, the amount of cooling water supplied on the downstream side is lower than on the upstream side, and the pressure of the cooling water is also lower on the downstream side than on the upstream side. Therefore, the amount of cooling water supplied decreases toward the downstream side, causing uneven cooling between the upstream and downstream sides, which may prevent uniform cooling across the multiple battery modules that make up the battery. .

Therefore, there is a need for a battery cooling system that can uniformly cool a plurality of battery modules.

A characteristic configuration of the battery cooling system according to the present invention is a battery cooling system that cools a battery module formed by stacking a plurality of cells, wherein each of the plurality of battery modules is accommodated in each battery module. A battery case having a plurality of storage parts, a main pipe through which cooling water discharged from a pump flows, a plurality of branch pipes branching from the main pipe and provided corresponding to each of the plurality of storage parts, and a plurality of branch pipes branching from the main pipe and provided corresponding to each of the plurality of storage parts. A supply unit provided at a tip of each of the branch pipes and supplying the cooling water to the battery modules housed in each of the housing parts, and a connection between the main pipe and the branch pipe from the pump. The present invention includes a flow rate control mechanism that increases the pressure loss of the cooling water flowing through the branch pipe that branches through the connection point as the distance to the connection point becomes shorter.

In this configuration, the cooling water branches from the main pipe to a plurality of branch pipes and flows, and the cooling water is supplied from each branch pipe to the battery module to cool the battery module. At this time, the shorter the distance to the connection point between the main pipe and the branch pipe, the greater the flow rate control mechanism that increases the pressure loss of the cooling water flowing through the branch pipe branching via the connection point. With this characteristic configuration, the pressure loss of the cooling water discharged from the pump is greater on the upstream side and smaller on the downstream side, which causes the inconvenience that the pressure of the cooling water is lower on the downstream side than on the upstream side. is prevented. As a result, the flow rate control mechanism can make the flow rate of the cooling amount flowing through each of the plurality of branch pipes branched from the main pipe uniform. Therefore, since the flow rate of cooling water supplied to each of the plurality of battery modules can be made uniform, it is possible to uniformly cool each of the plurality of battery modules.

Further, it is preferable that the flow rate control mechanism increases the pressure loss based on at least one of a reduction in the inner diameter of the branch pipe and an extension of the length of the branch pipe.

With this configuration, the flow rate of cooling water flowing through the branch pipes can be easily reduced by reducing the inner diameter of the branch pipes on the upstream side compared to the downstream side, or by extending the length of the branch pipes. can be made uniform. Therefore, each of the plurality of battery modules can be easily cooled uniformly.

The invention further includes a discharge part provided in each of the storage parts for discharging the cooling water, and a confluence part where each of the plurality of discharge parts joins, and the flow rate control mechanism is configured to move the pump from the confluence part to the confluence part. It is preferable that the shorter the distance to the outlet, the greater the pressure loss of the cooling water flowing through the discharge section.

The pressure of the cooling water returning to the pump is lower on the upstream side than on the downstream side, contrary to the pressure of the cooling water discharged from the pump. Therefore, as in this configuration, if the shorter the distance from the confluence part to the pump, the greater the pressure loss of the cooling water flowing through the discharge part, the pressure loss of the cooling water returning to the pump will be smaller upstream and downstream. Since the pressure loss becomes large, the inconvenience that the pressure of the cooling water is lower on the upstream side than on the downstream side can be prevented. As a result, the flow rate of the cooling water discharged from each of the plurality of storage parts can be made uniform. Therefore, it is possible to uniformly circulate the cooling water in each of the plurality of accommodating sections, so that it is possible to cool the plurality of battery modules more uniformly.

Further, in the case where the bottom surfaces of the accommodating portions are provided at the same height positions, liquid-to-liquid equalization that makes the liquid level of the cooling water in each of the accommodating portions uniform across a plurality of accommodating portions is provided. Preferably, a pressure pipe is provided.

With such a configuration, the liquid pressure equalization pipe can reduce variations in the liquid level of the cooling water in the plurality of storage sections. Therefore, since the height at which the battery modules are immersed in the cooling water can be made uniform, it is possible to make the cooling effect on each of the plurality of battery modules uniform.

Further, in the case where the bottom surfaces of the accommodating parts are provided at the same height positions, the pressure equalizing mechanism that equalizes the pressure of the gas phase in each of the accommodating parts over a plurality of the accommodating parts is provided. Preferably, it is provided above the liquid pressure equalization pipe.

With such a configuration, the pressure equalization mechanism that equalizes the pressure of the gas phase in the storage parts can further reduce variations in the liquid level of the cooling water in the plurality of storage parts. Therefore, since the height at which the battery modules are immersed in the cooling water can be made uniform, it is possible to make the cooling effect on each of the plurality of battery modules uniform.

1 is a diagram showing the configuration of a battery cooling system. It is a figure explaining the flow control mechanism in a supply route. It is a figure explaining the flow control mechanism in a discharge path. It is a figure which shows another example of a flow control mechanism. It is a figure which shows another example of a flow control mechanism. It is a figure showing an interliquid pressure equalization pipe and a pressure equalization mechanism. It is a figure which shows another example of a pressure equalization mechanism.

A battery cooling system according to the present invention is configured to cool a battery module formed by stacking a plurality of cells. A cell is the smallest unit of battery that constitutes a battery, and one battery module is constructed by connecting a plurality of cells in series. Further, for example, one battery (battery pack) is configured by connecting a plurality of battery modules in series, and connecting the battery modules connected in series in parallel. A battery cooling system is capable of cooling each battery module. Hereinafter, the battery cooling system 1 of this embodiment will be explained.

FIG. 1 is a diagram schematically showing the configuration of a battery cooling system 1. As shown in FIG. FIG. 2 is a diagram showing a cooling water supply path in the battery cooling system 1. FIG. 3 is a diagram showing a cooling water discharge path in the battery cooling system 1. As shown in FIG. As shown in FIGS. 1 to 3, the battery cooling system 1 includes a battery case 10, a main pipe 20, a branch pipe 30, a supply section 40, a flow control mechanism 50, a discharge section 60, and a confluence section 70. Ru. Note that, as the cooling water in this embodiment, a liquid having high electrical insulation properties, such as a fluorine-based inert liquid, is used, for example.

The battery case 10 has a plurality of accommodating portions 11 partitioned by intermodule plates 12 . In the battery case 10 of FIG. 1, four accommodating portions 11 are formed by partitioning by three inter-module plates 12. Each of the plurality of battery modules 2 is accommodated in the accommodating portion 11 . Therefore, one battery module 2 is accommodated in one accommodating portion 11 .

Cooling water discharged from the pump P is supplied to the battery case 10. A main pipe 20 is provided in communication between the pump P and the battery case 10. Therefore, the cooling water discharged from the pump P flows through the main pipe 20 and is supplied to the battery case 10.

A plurality of branch pipes 30 are provided to branch from the main pipe 20 . As described above, in this embodiment, the battery case 10 is provided with a plurality of (four) accommodating parts 11. The branch pipes 30 are provided corresponding to each of these four accommodating parts 11. Being provided in correspondence with each of the accommodating portions 11 means that the branch pipes 30 and the accommodating portions 11 are provided in a one-to-one correspondence. Therefore, the cooling water is configured to flow from the main pipe 20 to one predetermined accommodating portion 11 via one predetermined branch pipe 30 .

The supply unit 40 is composed of a nozzle, a straight pipe, etc. provided at the tip of each of the plurality of branch pipes 30. The supply unit 40 supplies cooling water to the battery modules 2 housed in the respective housing units 11 . As described above, the branch pipes 30 are provided corresponding to each of the accommodating parts 11, and the battery modules 2 are accommodated in the accommodating parts 11. Therefore, cooling water is supplied from the supply section 40 to the battery module 2 accommodated in the accommodation section 11 . This supply unit 40 can use a nozzle that discharges the cooling water flowing through the branch pipe 30 toward the battery module 2 as described above. Thereby, it becomes possible to directly spray cooling water onto the battery module 2. Therefore, the cooling water sprayed onto the battery module 2 can easily remove heat from the battery module 2, making it possible to enhance the cooling effect. The supply unit 40 can be configured so that the cooling water contains air bubbles, for example, or can be configured so that the cooling water is dispersed and released, like a shower head, for example.

The flow rate control mechanism 50 increases the pressure loss of the cooling water flowing through the branch pipe 30 that branches off via the connection point 29 as the distance from the pump P to the connection point 29 between the main pipe 20 and the branch pipe 30 increases. do. FIG. 2 shows the main pipe 20, branch pipes 30, and connection points 29 in the battery case 10. In this embodiment, the main pipe 20 corresponds to a flow path through which cooling water flows between the discharge port P1 of the pump P and the connection point 29. In this embodiment, the main pipe 20 includes a first main flow path 21 from the discharge port P1 of the pump P to the first branch point 24, and a second main flow path 22 from the first branch point 24 to the second branch point 25. It is constituted by a third main flow path 23 from a first branch point 24 to a third branch point 26. In this embodiment, two connection points 29 are provided, the second branch point 25 is one of the two connection points 29, and the third branch point 26 is the other of the two connection points 29. corresponds to

Here, in this embodiment, the branch pipe 30 is provided branching off from the main pipe 20 as described above. Furthermore, in this embodiment, four supply units 40 are provided as shown in FIG. 2 . For ease of understanding, the four supply units 40 are referred to as a supply unit 41, a supply unit 42, a supply unit 43, and a supply unit 44, respectively. In this embodiment, the branch pipe 30 connects the first branch channel 31 from the second branch point 25, which is one of the two connection points 29, to the supply section 41, and the first branch flow path 31, which is one of the two connection points 29. A second branch flow path 32 from a certain second branch point 25 to the supply section 42; a third branch flow path 33 from the third branch point 26, which is the other of the two connection points 29, to the supply section 43; A fourth branch channel 34 extends from the third branch point 26, which is the other of the two connection points 29, to the supply section 44.

In this embodiment, the second main flow path 22 is configured to be shorter than the third main flow path 23 (#1). Therefore, the flow rate control mechanism 50 is configured such that the pressure loss of the cooling water flowing through the first branch flow path 31 and the second branch flow path 32, which are branched via the second branch point 25, is divided via the third branch point 26. The third branch flow path 33 and the fourth branch flow path 34 are configured such that the pressure loss is greater than the pressure loss of the circulating cooling water.

Here, the flow rate control mechanism 50 increases the pressure loss based on at least one of reducing the inner diameter of the branch pipe 30 and extending the length of the branch pipe 30. In this embodiment, the flow control mechanism 50 is configured to increase the pressure loss by extending the length of the branch pipe 30. Therefore, the length (flow path length) of the first branch flow path 31 and the second branch flow path 32 is longer than the length (flow path length) of the third branch flow path 33 and the fourth branch flow path 34. It is configured as follows (#2). Thereby, the pressure loss of the cooling water flowing through the first branch flow path 31 and the second branch flow path 32 is made larger than the pressure loss of the cooling water flowing through the third branch flow path 33 and the fourth branch flow path 34. It becomes possible to do so. At this time, the third branch channel 33 and the fourth branch channel 34 are arranged so that the pressure of the cooling water in the supply section 41 and the supply section 42 is approximately the same as the pressure of the cooling water in the supply section 43 and the supply section 44. It is preferable to set the lengths of the first branch flow path 31 and the second branch flow path 32 with respect to the length of . Thereby, the pressures in the supply section 41, the supply section 42, the supply section 43, and the supply section 44 become approximately the same, and it becomes possible to reduce the difference in cooling effect for each battery module 2.

In this embodiment, as shown in FIG. 1, a portion of the main pipe 20, the branch pipe 30, the supply section 40, and the flow rate control mechanism 50 are formed on the upper plate 13 provided above the battery case 10. Ru.

FIG. 1 also shows a discharge route for cooling water introduced into the battery case 10. In addition, in FIG. 1, the discharge path is shown in an exploded state for easy understanding.

A discharge part 60 for discharging cooling water is provided at the bottom of each housing part 11. In the example of FIG. 1 , one accommodating part 11 is provided with one ejecting part 60 , but a plurality of ejecting parts 60 may be provided in one accommodating part 11 .

FIG. 3 is a diagram showing a flow path through which cooling water flows from the discharge part 60 of the battery case 10 to the suction port P2 of the pump P. In the example of FIG. 3, four discharge portions 60 are shown. For ease of understanding, these four discharge parts 60 are referred to as a discharge part 61, a discharge part 62, a discharge part 63, and a discharge part 64, respectively. The discharge part 61 communicates with a first discharge passage 65 , and the discharge part 62 communicates with a second discharge passage 66 . Furthermore, the discharge section 63 communicates with a third discharge path 67, and the discharge section 64 communicates with a fourth discharge path 68. In this embodiment, the discharge part 61 and the first discharge passage 65 are collectively referred to as the discharge part 61, the discharge part 62 and the second discharge passage 66 are collectively referred to as the discharge part 62, and the discharge part 63 and the third discharge passage 67. are collectively referred to as the discharge section 63, and the discharge section 64 and the fourth discharge path 68 are collectively referred to as the discharge section 64.

Each of the plurality of discharge parts 60 joins together at a joining part 70. In this embodiment, the merging part 70 between the first discharge passage 65 and the second discharge passage 66 is the first merging part 71, and the merging part 70 between the third discharge passage 67 and the fourth discharge passage 68 is the second merging part. 72. Therefore, the discharge part 61 and the discharge part 62 join together at the first merging part 71 , and the discharge part 63 and the discharge part 64 join together at the second merging part 72 .

Here, the flow rate control mechanism 50 increases the pressure loss of the cooling water flowing through the discharge section 60 as the distance from the merging section 70 to the pump P becomes shorter. The first merging portion 71 communicates with the fifth discharge path 73 , and the second merging portion 72 communicates with the sixth discharge path 74 . The fifth discharge path 73 and the sixth discharge path 74 merge at a third merging portion 75 . In this embodiment, the fifth discharge passage 73 is configured to be shorter than the sixth discharge passage 74 (#3). Therefore, in this embodiment, the third exhaust path 67 and the fourth exhaust path 68 are configured to be shorter than the first exhaust path 65 and the second exhaust path 66 (#4). Thereby, the pressure loss of the cooling water flowing from the discharge part 61 and the discharge part 62 to the first confluence part 71 is made larger than the pressure loss of the cooling water flowing from the discharge part 63 and the discharge part 64 to the second confluence part 72. can do. At this time, the sixth discharge to the fifth discharge passage 73 is adjusted so that the pressure of the cooling water flowing through the fifth discharge passage 73 and the pressure of the cooling water flowing through the sixth discharge passage 74 are equal to each other. It is preferable to set the length of the path 74. This allows the suction port P2 of the pump P to suck in cooling water from the discharge part 61, the discharge part 62, the discharge part 63, and the discharge part 64 in a well-balanced manner.

In this embodiment, as shown in FIG. 1, at least a portion of the discharge path from the battery case 10 described above is formed in the lower plate 14 provided on the lower side of the battery case 10.

Here, FIG. 4 shows another example of the flow rate control mechanism 50. In the example of FIG. 4, a main pipe 20 is provided from the discharge port P1 of the pump P, and this main pipe 20 is provided with four branch points 29Z from the pump P side. These four branch points 29Z are defined as a branch point 29A, a branch point 29B, a branch point 29C, and a branch point 29D from the side closest to the pump P, and a branch pipe 30 branching from the main pipe 20 at the branch point 29A is a branch pipe 30A, a branch pipe 30A, and a branch pipe 30A. A branch pipe 30 that branches from the main pipe 20 at a branch point 29B is called a branch pipe 30B, a branch pipe 30 that branches from the main pipe 20 at a branch point 29C is called a branch pipe 30C, and a branch pipe 30 that branches from the main pipe 20 at a branch point 29D is called a branch pipe 30D. Then, the inner diameter of the branch pipe 30A is smaller than that of the branch pipe 30B, the inner diameter of the branch pipe 30B is smaller than that of the branch pipe 30C, and the inner diameter of the branch pipe 30C is smaller than that of the branch pipe 30D. Thereby, it is possible to configure the pressure loss to gradually increase in the order of branch pipe 30D, branch pipe 30C, branch pipe 30B, and branch pipe 30A. In this case as well, the pressure of the cooling water released from each of the supply section 40 in the branch pipe 30A, the supply section 40 in the branch pipe 30B, the supply section 40 in the branch pipe 30C, and the supply section 40 in the branch pipe 30D is mutually controlled. It is possible to maintain the same level.

Another example of the flow rate control mechanism 50 is also shown in FIG. In the example of FIG. 5 as well, a main pipe 20 is provided from the discharge port P1 of the pump P, and this main pipe 20 is provided with four branch points 29Z from the pump P side. Also in this example, the four branch points 29Z are defined as a branch point 29A, a branch point 29B, a branch point 29C, and a branch point 29D from the side closest to the pump P, and a branch pipe 30 branches from the main pipe 20 at the branch point 29A. A branch pipe 30A branches from the main pipe 20 at the branch point 29B, a branch pipe 30B branches from the main pipe 20 at the branch point 29C, a branch pipe 30C branches from the main pipe 20 at the branch point 29D. If the pipe 30 is a branch pipe 30D, the branch pipe 30A has a longer flow path than the branch pipe 30B, the branch pipe 30B has a longer flow path than the branch pipe 30C, and the branch pipe 30C has a longer flow path than the branch pipe 30D. The flow path length is longer than that of the Thereby, it is possible to configure the pressure loss to gradually increase in the order of branch pipe 30D, branch pipe 30C, branch pipe 30B, and branch pipe 30A. In this case as well, the pressure of the cooling water released from each of the supply section 40 in the branch pipe 30A, the supply section 40 in the branch pipe 30B, the supply section 40 in the branch pipe 30C, and the supply section 40 in the branch pipe 30D is mutually controlled. It is possible to maintain the same level.

In this embodiment, the bottom surfaces 11B of the plurality of accommodating parts 11 are provided at the same height position, and the liquid level of the cooling water in each accommodating part 11 is made uniform across the plurality of accommodating parts 11. A liquid pressure equalization pipe 80 is provided. In FIG. 6, the bottom surfaces 11B of the four accommodating portions 11 are provided at the same height. The heights of the cooling water from the bottom surface 11B of the four housing parts 11 are respectively H1, H2, H3, and H4. The height of the cooling water is the height of the cooling water when the pump P is operating in an output state in which the battery module 2 is outputting electric power. In this embodiment, the liquid pressure equalization pipe 80 is provided below the lowest liquid level H1. Therefore, the liquid pressure equalization pipe 80 is provided in the cooling water. The liquid pressure equalization pipe 80 is provided across the four housing parts 11 that are adjacent to each other.

Furthermore, in the present embodiment, a pressure equalizing mechanism 90 that equalizes the pressure of the gas phase in each of the housing sections 11 is provided above the liquid pressure equalization pipe 80 over the plurality of housing sections 11 . In this embodiment, a breather valve is provided as a pressure equalization mechanism 90 on the top surface of each accommodating portion 11 . The breather valve opens when the pressure of the gas phase in the housing section 11 exceeds an allowable design value. As a result, even if the liquid level of the cooling water in each housing part 11 is at a different position as shown in FIG. 6, for example, a uniform pressure can be applied to the cooling water in each housing part 11, and this pressure The cooling water flows through the liquid pressure equalization pipe 80 in accordance with this, and it becomes possible to reduce variations in the liquid level of the cooling water in each housing section 11.

Furthermore, instead of the blizzer valve, the pressure equalization mechanism 90 may be provided with a gas phase pressure equalization pipe above H4, which is the highest liquid level at this time, as shown in FIG. Even in this case, similarly to the liquid pressure equalizing pipe 80, the gas phase pressure equalizing pipe is provided across the four housing parts 11 that are adjacent to each other. As a result, a uniform pressure can be applied to the cooling water in each housing part 11, and the cooling water flows through the liquid pressure equalization pipe 80 according to this pressure, and the liquid level of the cooling water in each housing part 11 is adjusted. It becomes possible to reduce the variation in.

[Other embodiments]
In the above embodiment, an example has been described in which the battery case 10 has four accommodating parts 11, but the number of accommodating parts 11 may be two or three. Further, the number may be five or more.

In the above embodiment, the flow rate control mechanism 50 was described as increasing the pressure loss based on at least one of the reduction of the inner diameter of the branch pipe 30 and the extension of the length of the branch pipe 30. The control mechanism 50 may be configured to increase the pressure loss by both reducing the inner diameter of the branch pipe 30 and extending the length of the branch pipe 30.

In the embodiment described above, the flow rate control mechanism 50 in the flow path through which cooling water flows from the discharge part 60 of the battery case 10 to the suction port P2 of the pump P is configured such that the length of the discharge flow path is increased to reduce the pressure loss of the cooling water. The explanation was given using an example of increasing the value. However, the flow rate control mechanism 50 in the flow path through which the cooling water flows from the discharge part 60 of the battery case 10 to the suction port P2 of the pump P reduces the inner diameter of the discharge flow path to increase the pressure loss of the cooling water. It may be configured as follows.

INDUSTRIAL APPLICATION This invention can be used for the battery cooling system which cools the battery provided with several battery modules.

1: Battery cooling system 2: Battery module 10: Battery case 11: Storage section 11B: Bottom surface 20: Main pipe 29: Connection point 30: Branch pipe 40: Supply section 50: Flow rate control mechanism 60: Discharge section 70: Merging section 80: Liquid pressure equalization pipe 90: Pressure equalization mechanism P: Pump

Claims (5)

A battery cooling system that cools a battery module formed by stacking a plurality of cells,
a battery case having a plurality of accommodating portions for accommodating each of the plurality of battery modules;
A main pipe through which cooling water discharged from the pump flows,
a plurality of branch pipes branching from the main pipe and provided corresponding to each of the plurality of accommodating portions;
a supply section that is provided at the tip of each of the plurality of branch pipes and supplies the cooling water to the battery module accommodated in each of the accommodation sections;
A flow rate control mechanism that increases the pressure loss of the cooling water flowing through the branch pipe branching through the connection point as the distance from the pump to the connection point between the main pipe and the branch pipe increases. Equipped with battery cooling system. The battery cooling system according to claim 1, wherein the flow rate control mechanism increases the pressure loss based on at least one of a reduction in the inner diameter of the branch pipe and an extension of the length of the branch pipe. a discharge section provided in each of the storage sections for discharging the cooling water;
further comprising a merging part where each of the plurality of discharge parts joins,
3. The battery cooling system according to claim 1, wherein the flow rate control mechanism increases the pressure loss of the cooling water flowing through the discharge section as the distance from the merging section to the pump becomes shorter. In the case where the bottom surfaces of the accommodating portions are provided at the same height position,
3. The battery cooling system according to claim 1, further comprising a liquid pressure equalizing pipe that equalizes the liquid level of the cooling water in each of the plurality of accommodation sections. In the case where the bottom surfaces of the accommodating portions are provided at the same height position,
5. The battery cooling system according to claim 4, further comprising a pressure equalizing mechanism that equalizes the pressure of the gas phase in each of the plurality of accommodation sections above the liquid pressure equalization pipe.

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